Hi David, I have heard a complaint from somewhere in the past that the ECU responds to the information from a sensor rather than a problem in the engine -- which it is supposed to do. The conclusion must be, that if the engine is running properly,then the sensor is unable to send the right message because the sensor itself is faulty. I had an issue yesterday with the oil in my 2.7 D engine. The dipstick was saying that there was too much oil. My mechanic checked it out, took out some oil, dipped the oil again and found that there was an indication that there was still too much oil in, when we knew that there wasn't. There was no water in the oil,either. We concluded that the dipstick design, which is rather curious was dragging up oil when it was being taken out, and so giving a false reading. Regards, Peter.